Fittings employed at the end of conduits take a variety of forms, such as adapters, tees, elbows, etc., and smooth wall conduits such as copper pipe, may be attached to the fittings by several systems, such as by brazing or soldering, flares, upset or flanged ends, compression rings, or the like. Each type of interconnection between the conduit and fitting requires a particular fitting configuration, and with some modes of connection, the conduit end must be worked, such as flared or upset. Except for the brazed or soldered connections, a rotatable nut is usually mounted upon the conduit for attachment to fitting threads.
In view of the variety of connection systems available suppliers of OEM equipment such as refrigeration units, air conditioners, and the like, must decide which type of fitting to employ without knowing the type of conduit connections preferred by their customers, or which will be used with the equipment being sold. Thus, it is often necessary for distributors, dealers, installers, etc. to maintain a large inventory of various types of fittings to accommodate the particular installation desired. While convertible or multi-purpose conduit fitting connections are known, such known fittings are too costly, or complicated, to enjoy commercial success, or do not lend themselves to diverse installation. The following United States patents illustrate convertible or multi-purpose fittings previously proposed but not commercially available: U.S. Pat. Nos. 1,820,020; 2,159,811; 2,824,756; 2,489,928 and 3,126,212.
It is an object of the invention to provide a convertible fitting usable with conduit or tubing to selectively produce either a brazed, soldered or flared connection thereby substantially reducing inventory requirements.
Another object of the invention is to provide a fitting for conduit or tube wherein either a brazed, soldered or flared connection may be used, and when utilizing a flared connection an inexpensive insert is employed, the insert construction being such that tightening of the flare nut simultaneously seals the conduit flare to the insert and seals the insert to the fitting with a metal-to-metal seal.
In the practice of the invention the fitting includes an internal passage which is provided with a concentric counterbore intersecting an end surface. Externally, the fitting is provided with threads concentric to the passage adjacent the fitting end. The cylindrical counterbore permits the end of a cylindrical conduit or tube, such as copper tube, or the like, to be inserted thereinto, and connected to the fitting by conventional brazing or soldering techniques.
If a flare is formed upon the end of the conduit, an annular insert is located within the fitting counterbore and the insert includes a head having a conventional conical surface for cooperation with the conduit flare. The insert head is also provided with a homogeneous ridge in axial alignment with the fitting end, the ridge having a sharpened apex wherein tightening of a standard flare nut upon the fitting threads forces the conduit flare upon the insert conical surface, and simultaneously axially displaces the insert into the fitting counterbore to slightly embed the insert ridge into the fitting end producing a fluid tight metal-to-metal seal between the insert and fitting, as well as produce a fluid tight seal between the insert and flare.
The manufacture of fittings in accord with the invention requires no unusual machining techniques, may be economically achieved, and the insert is also a low cost high production part which may be economically discarded if a flare connection is not desired.